I used to be one of the people that thought a crate was cruel until I got my newest dog. He's never had a problem with using the bathroom in the house so that wasn't a problem. However, when I would leave he would find something to tear up. I already couldn't leave him outside because he could jump/climb a 6-foot fence. And, he just walked right through the screen in our screened-in-porch. He was driving me crazy! I tried a tie-out, but he kept getting loose from that too.
Finally, I had to try the crate. It's been a life-saver! He only goes in it when I'm gone and doesn't sleep in it at night unless he's staying somewhere other than home.
Also, my other dog has actually taken over his crate when I leave it open. She feels safer in it. They will both go in it on their own as long as there is a bed in it.
Anyway, the point is, I believe that crates are fine, but I probably would only use it as a last resort. Mainly because they are expensive and heavy since my dogs are very large dogs.